Gas chromatographic quantification of aliphatic aldehydes in freshly distilled Calvados and Cognac using 3-methylbenzothiazolin-2-one hydrazone as derivative agent

A new precise and sensitive method was used for the quantification of aliphatic aldehydes from C5 to C11 in highly ethanolic beverages such as freshly distilled spirits. Carbonyl compounds were derivatized using 3-methylbenzothiazolin-2-one hydrazone (MBTH) and then separated and detected by gas chromatography–mass spectrometry (GC–MS). Selective mass spectrometric detection of molecular ions of derivatives was performed to obtain a good sensibility (0.2–1.2 μg l−1) and a good selectivity. For a concentration of 20 μg l−1, relative standard deviations were lower than 10% except for heaviest compounds (decanal and undecanal) where RSD were between 11 and 13%. The concentrations of aliphatic aldehydes were determined in nine samples of freshly distilled Calvados and two samples of freshly distilled Cognac with highest concentrations reported for 3-methylbutanal (from 170 to 1220 μg l−1 in Calvados and from 1540 to 5500 μg l−1 in Cognac). 3-Methylbutanal and hexanal, due to their low detection thresholds, could be important olfactive markers of these two products. Less than 1h30 is required to quantify the nine studied aliphatic aldehydes in freshly distilled spirits.